212 THE NATURAL HISTOET REVIEW. 



But this Port Juvenal Flora is eminently adventitious ; the idea 

 which some entertain that it is a kind of botanic garden where the 

 botanist may at any time make a rich herborisation, is quite 

 erroneous. The 458 species are the result of repeated collections, 

 made during more than forty years, of plants, of which the greater 

 part only subsist a single season, or have been known only in single 

 individuals. These are chiefly annual Papilionacese, Cruciferae, 

 Gramineae, &c. A few such as Centaurea iberica, G. diffusa^ Verhas- 

 cum cuspidatum, V. mucronatum, JEgilops cylindrica, JE. ventricosa^ 

 &c., are annually renewed in the same locality. One of these, 

 V. mucronatum, was supposed to have spread to Gramont, where, 

 however, it has now disappeared. One only of the whole number, 

 Onopordon virens^ DC. (0. tauricwni) has become generally dispersed 

 along the river, and has all the appearance of a definitive naturaliza- 

 tion. In the wool- washing grounds of Bessan, which lasted but a 

 few years, six species were found, all of which have now disappeared. 



The ballast-heaps about the ports of the Lez, and of Cette, were 

 specially examined in the years 1856, 1857, and 1858, when thirty- 

 three exotic species were found, of which three only have become 

 permanent, Onopordon virens (also introduced as above, with wool), 

 Amhrosia tenuifolia, and Asclepias curassavica, the two latter occu- 

 pying only a very limited space. 



After having thus shown in detail what have been within the last 

 three centuries the exotic species purposely sown or planted, or 

 unintentionally scattered in the region, Dr. Planchon, in summing 

 up the effect on the vegetation of the country, concludes that 

 of the numerous germs thus confided to the soil, the greater number 

 have perished without any result ; others, to the amount, as far as 

 observed of five or six hundred species, have risen and gone through 

 their dilTerent stages of development, and then passed away, without 

 taking definitive possession of the soil. 



A few (among which three — Anemone coronaria, Tulipa oculussolis 

 and Nigella sativa — are specially mentioned) have shown more per- 

 sistence, and are still found, but only in the midst of certain culti- 

 vations, changing place with them, and constantly liable to disappear. 



Four or five escapes from cultivation have established themselves 

 repeatedly on the banks and ditches of the fields in which they 

 originated, but without any tendency to invade fresh spaces. 



Sixteen species have become really naturalized, although even 

 these show it in difierent degrees, for six of them are only to be 

 found within the enclosures or limited spaces where they were first 



